The present invention pertains primarily to lawnmowers, and more particularly to power lawnmowers.
It is generally well known that power lawnmowers produce a noticeable and very often an annoying amount of noise during their operation. Although gas-powered lawnmower motors normally produce more noise than electric lawnmower motors, both generate sufficient resonance and resulting noise to induce lawnmowers manufacturers to consider reasonable noise levels as one of the many requirements during design of a new lawnmower. Some European countries, such as West Germany, have laws regulating the noise levels of lawnmowers, and actually restrict the use of those mowers that do not meet strict db levels to specified periods of the day.
One approach at reducing the noise problem has been to use motors which generate less noise. However, this normally results in the use of a smaller less powerful motor. In any attempt at reducing noise problems, therefore, special consideration should be given to maintaining sufficient power levels to enable efficient operation, as well as accommodating the other necessary criteria of lawnmower operation, including cooling of the motor by circulating air, and maintaining the relatively low profile and manuverability of the lawnmower.
Accordingly, it is a principal object of the present invention to provide sound absorption for a power lawnmower which in addition to reducing noise levels, enables the production of a lawnmower without drastic modifications to the design, operation, size, or weight of the mower, while at the same time actually increasing the structural integrity of the lawnmower body.
In general, the sound absorption arrangement for power mowers according to the present invention contemplates the use of rigid sound absorbing material that is configured to conform to the interior volume between the motor and the mower housing. The material thus serves to not only attenuate the noise generated by the motor but also serves to add structural support to the mower housing. In addition, the sound absorbing sub-assembly is preferably adhered to the interior surfaces of the housing to dampen the resonances of the lawnmower body caused by vibration transmitted from the mower. Moreover, in the preferred embodiment of the present invention the sound absorbing material is also used to define air passages within the mower housing for directing the flow of cooling air through the body around the motor.
Additional advantages and features of the present invention will become apparent from a reading of the detailed description of the preferred embodiment which makes reference to the following set of drawings in which :